The long-term goal of this project is to characterize and quantify the apolipoproteins and lipoprotein families as the carrier components of lipid transport system in humans and selected animal species. These studies are based on the concept according to which plasma lipoprotein system consists of families of lipoproteins each of which is characterized by a single, distinct protein moiety as the main differentiating chemical criterion. The specific aims of the proposed research are: 1) Characterization and quantitative determination of apolipoproteins and lipoprotein families in plasma and major density classes of men and women with a) normal serum lipid concentrations, b) specific types of primary hyperlipoproteinemia, and c) diabetes mellitus, the nephrotic syndrome and hypothyroidism; 2) structure and formation of the abnormal low density lipoprotein (LP-X) in patients with obstructive jaundice; 3) characterization and quantitative determination of apolipoproteins and lipoprotein families in plasma and major density classes of some selected animal species.